Brian Gullett, PhDUS EPA Office of Research and Development (ORD)

EPA Tools & Resources WebinarFebruary 17, 2021

EPA PFAS INNOVATIVE TREATMENT TEAM (PITT) FINDINGS ON

PFAS DESTRUCTION TECHNOLOGIES

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Per- & Polyfluoroalkyl Substances (PFAS)

• A very large class of synthetic chemicals– Chains of carbon (C) atoms surrounded by fluorine (F)

atoms, with different terminal ends– Complicated chemistry – thousands of different

variations exist in commerce– Widely used in industrial processes and in consumer

products– Mobile via multiple air, water pathways– Some PFAS are known to be PBT:

• Persistent in the environment• Bioaccumulative in organisms• Toxic at relatively low (ppt) levels

Fluorine

PFOA PFOS 2

Outline• EPA PFAS Innovative Treatment Team (PITT)• Goals• Challenges• Non-Combustion Technologies

• Mechanisms

• Combustion Technologies• Mechanisms

• Outputs• Status and PITT Legacy, Next Steps

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps3

PFAS Innovative Treatment Team (PITT)

• Full-time team of multi-disciplined EPA research staff • Focused efforts and expertise on a single problem: how to remove,

destroy, and test PFAS-contaminated media and waste• For 6 months, the PITT worked to achieve the following goals:

• Assess current and emerging destruction methods being explored by EPA, universities, other research organizations and industry

• Explore the efficacy of methods while considering byproducts to avoid creating new environmental hazards

• Evaluate methods’ feasibility, performance and costs to validate potential solutions

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PITT Goals

• Develop a “Toolbox” of reviewed solution(s) for the destruction of PFAS in media and contaminated waste to meet the needs of EPA programs and regions, states and tribes, federal agencies, and industry

• Traditional (combustion) destruction• Temperature and time conditions for C-F bond breakage• Performance of flue gas cleaning systems• Analysis of byproducts

• Innovative (high risk), non-traditional approaches• Destruction performance• Byproducts

• Provide decision makers with state of the science data on incineration effectiveness enabling them to better manage end-of-life disposal of PFAS-containing materials

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PFAS Sources Considered

• Biosolids, sludge• Aqueous film forming foam (AFFF)-

contaminated soils• AFFF concentrate, spent AFFF• Municipal Waste Combustors

(MWCs), landfills, landfill leachate• Spent granular activated carbon

(GAC), anion exchange resins

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PITT Challenges

• COVID-19• Building closures• Lab closures• Restricted partner access to labs • Closure of suppliers• Unavailable instrument repairs

• Finding field test partners • Concurrent field sampling and sampling methods

development

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps7

Challenges of PFAS Destruction

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• Complicated chemistry ‒ thousands of PFAS exist• Widely used in industrial processes and consumer

products• Efficacy of thermal treatment

• C-F bond is the strongest bond in organic chemistry• Emission sampling and analytical methods are under

development• Volatile, non-volatile, polar, non-polar• Limited number of analytical standards available

• Field data lacking• Historical laboratory research on “destructibility” lacks

information about products of incomplete combustion (PICs)

~90 ⁰C

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Non-Combustion Technologies Selected• Chemical• Biological• Plasma• Mechanochemical• Sonolysis• Ebeam• UV• Supercritical water oxidation• Deep well injection• Sorption/stabilization• Electrochemical• Landfill• Land application• Pyrolysis

Assessment Factors:• Technology readiness• Applicability• Cost• Required development remaining• Risk/reward of technology adoptionAssessment Methods:• Subject matter expert discussions• Literature reviews• PITT discussions

Technologies selected for further investigation

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps9

Mechanochemical TreatmentWorks by:• Introduction of dry solids into a ball mill• Co-milling reagents: Al, Fe, SiO2, CaO, MgO, Al2O3, KOH,

NaOH, MnO2, TiO2• High energy ball impacts fracture solids generating localized

high temperatures and radicals that react and breakdown organic molecules

• Technology derived from Persistent Organic Pollutants (POPs)-contaminated soil treatment

• EDL (NZ) showed >99.8% DRE of PCBs in 45 min (US Navy, Hunters Point, 2006).

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

C(s) + CO2 + F-Y·

Bulley, M.; Black, B. EDL

Status:• Contract with EDL (New Zealand)

• AFFF impacted soil study• >99% destruction of targeted PFAS

• AFFF destruction study• AFFF added to sand• >99% destruction of targeted PFAS

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Electrochemical Treatment

Status:• Testing AECOM reactors

• Dilute AFFF• Data gaps:

• Uncertain byproducts• Volatile loss• Matrix effects

• Results expected by May ’21• 36 targeted PFAS• TOP (precursors assay)• TOF (total organic fluorine)

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Works by:• A high overpotential (>3 V) is applied to

an electrolytic cell• Stepwise degradation ultimately

produces CO2 and fluoride

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Supercritical Water Oxidation (SCWO)

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

At T = 374oC and P = 221 Bar, water becomes supercritical and organics are solubilized and oxidized

Status:• Focus on AFFF concentrate (stockpile destruction alternative)• In-house lab study on Hydrothermal oxidation

• Progressing on track• Experiments complete, chemical analysis complete• Up to 99% destruction of targeted PFAS seen by 3 vendors

• Aquarden (Denmark) – Analyzed targeted PFAS • Battelle’s SCWO “Annihilator” – Analyzed targeted PFAS and fluoride• 374Water/Duke – Analyzed targeted PFAS, TOF, and fluoride

• General Atomics MCRADA – Plan under review, experiment in summer ‘21

Works by:

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SCWO Status

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Battelle:Bench Scale 100x dilute AFFF concentrate Target PFAS in and out (liquid)Archived samples (non-target)

374Water:Pilot scale (Test #1: 9/10/20)4 experiments, varying dilute AFFF Target PFAS in and out (liquid)Archived samples (non-target)Canister and sorbent samples (air)

Aquarden: Working unit (pilot test)100x dilute AFFF concentrateTarget PFAS in and out (liquid)

General Atomics:Working unit (pilot test)Varying dilute AFFF Target PFAS in and out (liquid)Archived samples (non-target)Canister and sorbent samples (air)

MCRADA signed

AFFF Concentrate

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Biosolids Pyrolysis/Gasification

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Status:• Field test of Pyrolysis unit (with emission controls)

that produces Biochar with energy to a biosolids dryer

• Field test completed 2020 and sampled for PFAS in:- Input Biosolids- Produced Biochar- Scrubber Water - Multi-position FTIR

• No reportable PFAS found in produced biochar, but additional research needed to understand potential releases to air and water.

Works by:• Pyrolysis is a process that decomposes materials at

moderately elevated temperatures in an oxygen-free environment.

• Gasification is similar to pyrolysis but uses small quantities of oxygen, taking advantage of the partial combustion process to provide the heat to operate the process.

• The oxygen-free environment in pyrolysis and the low oxygen environment of gasification distinguish these techniques from incineration.

• Pyrolysis, and certain forms of gasification, can transform input materials, like biosolids, into a biochar while generating a hydrogen-rich synthetic gas (syngas).

BioForceTechcommercial scale

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Combustion Technologies Status• Laboratory studies

• At EPA (Rainbow furnace)• Indicators for Destruction Removal

Efficiency (DRE) and Products of Incomplete Combustion (PICs)

• FTIR applicability• At University of Dayton Research Institute

• Temperature (T), time (t) effects• Byproducts• Flame radical studies• Spent GAC/Ion Exchange resin

• Pursuing field sampling efforts at facilities with different types of combustion process

• Muncipal Waste• Wastewater Treatment• Rotary Kiln Incineration

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Rainbow Furnace RTP, NC campus

Works by:• Bond breakage via gas

phase oxidation reactions with organic PFAS

• Ideally, formation of CO2, H2O and HF

• HF removed in acid gas scrubber

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Guide on Waste/Technology Applicability and Design Considerations – Waste Characteristics

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Waste Characterization

Waste Scale

Spent GAC/AEX

Soils

AFFF & Spent AFFF

Leachate

Biosolids/Sludges

• Excavated solids, low PFAS/soil mass ratio, high volumes

• Spent GAC & AEX are solids with binding sites saturated with a combination of PFAS and co-contaminants

• High moisture content, relatively low PFAS concentrations, co-contaminants

• Liquid phase, legacy AFFF ~5% PFAS• Spent AFFF is dilute

• Liquid phase with organic co-contaminants

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Crosswalk of Wastes and Technologies –Design Issues

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System Sizing

•Continuous vs. Batch Processing

•Level of treatment required

•Transportability•Centralized or

decentralized treatment

ProcessConsiderations

•Phase of material to be treated

•Chemical Inputs•Energy Inputs•Capital and

Operating Costs•Lifecycle

considerations

Waste Steams

•Side Stream Generation•Phase Change?

•Additional Unit Process Treatment (e.g., Pollution Control Devices)

Final Disposition

•Further treatment of co-contaminants

•Disposal•Environmental

Release

Treatment Selection Process Management

Electrochemical Treatment

Supercritical Water Oxidation

Mechanochemical Milling

Pyrolysis

Inno

vativ

e Tr

eatm

ent

Tech

nolo

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Engineering Design Considerations• Size is a function of kinetics and reactor

configuration• High lifecycle and operating costs• Minimum concentration threshold• High lifecycle and operating costs• Technically complex• Size is a function of kinetics and reactor

configuration• May be limited by water conc. allowable

• Can be batch or continuous• Dry or semi-dry solids only

• May generate gas phase waste stream• Can generate perchlorate in the presence of Cl

• Degradation byproducts may vary• Potential corrosion issues

• Likely generates gas phase waste stream• Ancillary unit operations are necessary

• Pretreatment of solids to reduce water• Volatiles require treatment

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps17

PITT Introductory Paper on Four Innovative Technologies Studied

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Phase TRL Description

Rese

arch

1 Basic Principles observed

2 Technology concept formulated

3 Experimental proof of concept

Dev

elop

men

t

4 Technology validated in lab

5 Technology validated in relevant environment

6 Technology demonstrated in relevant environment

Dep

loym

ent 7 System prototype demonstration in operational environment

8 System complete and qualified

9 Actual system proven in operational environment

https://www.twi-global.com/technical-knowledge/faqs/technology-readiness-levels

Electrochemical SCWO Mechanochemical Milling

Pyrolysis

Spent GAC/AEX N/A N/A TRL 210 TRL 1

Soils N/A N/A TRL 58 TRL 1

Biosolids/Sludges N/A TRL 56 TRL 1 TRL 79

Unused and spent AFFF

TRL 5/61,2 TRL 54,5,6,7 N/A N/A

Leachate TRL 43 TRL 45 N/A N/A

TRLs of Technology & PFAS Matrices

BASIS1 (AECOM) 2(Schaefer et al 2019)3 (Pierpaoli et al 2020)4 (General Atomics)5 (Aquarden) 6(374Water) 7(Battelle)8(EDL)9(BioForceTech)10(PITT)

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

• PFAS problem• 5 waste characteristics• 4 innovative technologies• Crosswalk of wastes and technologies• Technology readiness level

PITT Research Briefs

SCWO Electrochemical Oxidation Ball Milling Pyrolysis & Gasification

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

https://www.epa.gov/chemical-research/pfas-innovative-treatment-team-pitt

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https://www.epa.gov/innovation/innovative-ways-destroy-pfas-challenge• Goal: Novel, alternative, non-incineration methodologies that offer a

pathway to complete destruction of PFAS compounds found in unused PFAS-containing aqueous film forming foam (AFFF), a type of fire suppressant agent, while not creating hazardous byproducts

• Up to $50K for the best design concept for non-thermal technologies

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Challenge Partners• US Dept. of Defense: Strategic Environmental

Research and Development Program (SERDP) & Environmental Security Technology Certification Program (ESTCP)

• Environmental Council of the States (ECOS)/Environmental Research Institute of the States (ERIS)

• Colorado Department of Public Health & Environment

• Michigan Department of Environment, Great Lakes, & Energy

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Challenge Status

The numbers:• 212 solvers• 64 submissions from 18 countries• 23 solvers met the minimum acceptable criteria

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Aug• 25th Challenge Launched

Sept• 16th Public Webinar

• Est 500 Participants

Nov• 23rd Challenge Closed

Dec• 18th First round judging complete

• Some solvers notified of elimination

Jan• 18th Judging Panel Selection• 25th Propose Winners to Management

Feb• Winner Announced

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

Summary of PITT Findings

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps

• Preliminary results in laboratory and pilot-scale treatment systems demonstrate up to 99% loss of the initial PFAS compounds in the contaminated waste

• Thermal incineration/combustion• Supercritical water oxidation• Pyrolysis/gasification• Electrochemical oxidation, and • Mechanochemical treatment.

• Still unknown, however, is what PFAS byproducts, if any, are formed from each of these technologies.

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Next Steps• Continue laboratory and pilot-scale research and development efforts on:

• Non-combustion, innovative technologies• Thermal catalytic/incineration/combustion, • Supercritical water oxidation, • Pyrolysis/gasification, • Electrochemical oxidation, and • Mechanochemical treatment.

• Thermal/combustion technologies• Identify potential fluorinated byproducts formed during the application of these

treatment approaches (non-target compound analyses)• Explore opportunities for field sampling, development efforts with industrial and utility

facilities• Summarize efforts on non-combustion, innovative technologies in scientific papers

(spring 2021)• Promote next stage development for winners of the Innovative Ways to Destroy PFAS

Challenge

PITT Goals Challenges Non-Combustion Combustion Outputs Next Steps23

https://www.epa.gov/chemical-research/pfas-innovative-treatment-team-pitt

The views expressed in this presentation are those of the author and do not necessarily represent the views or policies of the US EPA. Any mention of trade names, products, or services does not imply an endorsement by the US

Government or EPA. EPA does not endorse any commercial products, services, or enterprises.

Contacts

Brian GullettLead, PITT TeamCenter for Environmental Measurement and ModelingUS EPA Office of Research and Development919-541-1534Gullett.Brian@epa.gov

Tim WatkinsDirectorCenter for Environmental Measurementand ModelingUS EPA Office of Research and Development919-541-5114 Watkins.Tim@epa.gov

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